The present invention relates to an image pick-up apparatus, and more particularly, to a camera type image pick-up apparatus for use in picking up pictures with light of fluorescent lamp in an ordinary room.
Conventionally, it is called "flicker" that quantity of light varies in response to the utility power frequency. An object illuminated by a light source with the flicker, such as fluorescent lamp, is often picked up by a camera having a linear image sensor. In such a case, a noise composed of a pattern of lateral stripes inevitably appears on the picked up image, when a period of driving the linear image sensor is nearly equal to that of flicker. A quality of the image is deteriorated by the noise of the pattern of lateral stripes.
A conventional image pick-up apparatus is disclosed, for example, in Japanese Unexamined Patent Publication 203286/1995 with a proposal for preventing the noise of the pattern of lateral stripes. In the conventional image pick-up apparatus disclosed in the Japanese Unexamined Patent Publication 203286/1995, as will later be described more in detail, a compensation is carried out by the use of a part of an image signal obtained from a camera by picking up an image of an actual object. It is therefore required that a reflectivity in a visual field extracting flicker components is kept constant. When an object such as a hand, an eraser, and an original copy, lies in the visual field extracting flicker components, image signals are subjected to deviation influenced by the obstacles. In the conventional image pick-up apparatus, such a deviation of image signals cannot be distinguished from that caused by flicker. As a result, the compensation cannot be correctly carried out in the conventional image pick-up apparatus.